In Scotland? I don't think so. In the world, ever? Certainly, there's examples from America, which means it's not impossible to become a thing here at some point.

My worry is more about the point of barring certain people from being able to hold office rather than the specifics of why they're being barred.

If somebody is on the sex offenders list, in a proportionally representative democracy, with a healthy fourth estate, I would hope that would be requirement enough to prevent them from becoming an MSP. If they still managed to get elected, I would hope it's because they managed to prove their reason for being on the list was spurious. It erodes trust in fair and free elections the bigger the list becomes of who can not set the rules.

I know it's a slippery slope argument, but after years of reading other countries' news, it feels a legitimate worry to have. Governments come and go, just because we have a good one now doesn't mean we will in the future. Laws like this could be abused to prevent "undesirables" from holding office.